An engine of a drive source, arranged in an engine compartment in a front portion of a vehicle, is elastically supported on a vehicle body by a plurality of engine mounts. The engine tends to oscillate based on torque fluctuations or rotation fluctuations which result from throttle manipulation or the like, and the engine oscillates with respect to the vehicle body by an amount equivalent to elastic deformation of the engine mounts which are installed to prevent engine vibrations from being transmitted to the vehicle body. Thus, the engine and suspension member are connected by a torque rod to reduce engine oscillations.
Incidentally, the suspension member connected with one end of the torque rod, is arranged below the engine compartment of the vehicle, this suspension member supports suspension arms so as to be capable of swinging in an upper and lower direction at the left and right ends of the engine compartment respectively, and the suspension member connects a pair of apron side members which are arranged on left and right sides of the engine compartment respectively, along a front and rear direction of the vehicle, thereby rigidity of the vehicle body is increased.
Conventionally, the above suspension member is formed into a closed sectional shape (a hollow closed structure made by joining two case halves together) by welding press-formed sheet metal. It is common practice for a torque rod mounting portion to be installed inside such a suspension member made of sheet metal (see, for example, Patent Literature 1).
Recently, on the other hand, for the purposes of weight reduction, productivity improvement, and the like, the suspension member has come to be formed integrally by casting (such as die casting) a light alloy, such as a light-weight aluminum alloy (see, for example, Patent Literature 2).